Electromagnetic material handling system utilizing offset pole spacing

ABSTRACT

A technique of moving electrically conductive non-magnetic particles wherein a plurality of electromagnets are positioned on either side of an air gap with each electromagnet facing a nonmagnetic space between electromagnets on the opposite side of the air gap. The electromagnets are energized with polyphase current in a manner to generate a sweeping magnetic flux down the air gap for moving particles therealong. Eddy currents generated by one magnetic field relative phase reacts with flux of another magnetic field relative phase to provide motion of the article. Two specific utilizations of this technique are described; the separation of conductive non-magnetic particles from waste material and the movement of aluminum can lids.

United States Patent [191 Benowitz [111 3,824,516 July 16, 1974ELECTROMAGNETIC MATERIAL HANDLING SYSTEM UTILIZING OFFSET POLE SPACINGInventor: Sander Benowitz, 1537 Bedford Ave., Sunnyvale, Calif. 94087Filed: Feb. 5, 1973 Appl. No.: 329,587

[52] US. Cl 335/284, 335/289, 209/212, 198/41 Int. Cl. HOlf 13/00 Fieldof Search 335/219, 250, 289, 290,

References Cited UNITED STATES PATENTS Troy 209 212 Baker l98/4l-XBenson et a]. 209/212 Ioffe et al. l98/4l X Primary Examiner-GeorgeHarris Attorney, Agent, or Firm-Limbach, Limbach &

Sutton [5 7] ABSTRACT A technique of moving electrically conductivenonmagnetic particles wherein a plurality of electromagnets arepositioned on either side of an air gap with each electromagnet facing anon-magnetic space between electromagnets on the opposite side of theair gap. The electromagnets are energized with polyphase current in amanner to generate a sweeping magnetic flux down the air gap for movingparticles therealong. Eddy currents generated by one magnetic fieldrelative phase reacts with flux of another magnetic field relative phaseto provide motion of the article. Two specific utilizations of thistechnique are described; the separation of conductive non-magneticparticles from waste material and the movement of aluminum can lids.

13 Claims, 9 Drawing Figures PAIENIEBJUL 1 6 I974 sum 3 n? 3 FIIELECTROMAGNETIC MATERIAL HANDLING SYSTEM UTILIZING OFFSET POLE SPACINGBACKGROUND OF THE INVENTION is then passed through an air classifier forremoval of the light fractions such as paper. The heavier fractions,such as metals, glass, wood, rubber, plastics and rocks, remain forseparation into their various constituents. Ferrous metals are easilyremoved with existing magnetic equipment.

Separation of non-ferrous metal particles from the heavier fractions ofshredded waste material is more difficult. Non-ferrous metals includevaluable aluminum and copper. Manual separation is possible but this istedious and expensive. A flotation process is available for separationon the basis of specific gravity, but such wet process is difficult tocontrol and it is messy. A dry process based upon eddy current reactionsis described in U.S. Pat. No. 3,448,857 but such a process is limited tovery small sized non-magnetic particles.

Therefore, it is an object of the present invention to provide a methodand apparatus for removal of electrically conductive, non-magnetic metalparticles of a wide range of sizes from shredded waste material in asimple and inexpensive manner.

Problems similar to the separation of waste material exist in otherareas in industry for handling odd shaped electrically conductivenon-magnetic articles. For example, aluminum can ends are widelyemployed both with aluminum can bodies and steel can bodies in formingcompleted can. Aluminum can ends are fabricated by automatic machineryat a high rate of speed and in a large volume. Conveying systems areused for moving and storing the can ends between work stations, storageareas and assembly areas. Presently, can ends are generally propelledwith air jets or moved on conveyor belts that are provided with holesthrough which a vacuum provides a holding force for the can ends on theconveyor. Three existing systems are cumbersome, noisy and requirecontinuous maintenance. Furthermore, they are limited to straight linemotions of the can ends. Therefore, it is another object of the presentinvention to provide an electromagnetic conveying method and apparatusfor moving non-magnetic, electrically conductive articles such asaluminum can ends from one location to another.

It is a primary and more general object of the present invention toprovide an improved electromagnet assembly for efficient movement ofelectrically conductive, non-magnetic articles.

SUMMARY OF THE INVENTION' tromagnetic poles, each row having wide spacesof nonmagnetic material between successive magnetic poles,

2 and the poles of one row are positioned to be opposite a space betweenpoles of the other row. Each pole has a width that is about the same asits opposing nonmagnetic space. The electromagnets are excited in a wayto provide alternating magnetic fluxes of two different relative phasestravelling across the air gap between adjacent pole edges.

This particular magnetic pole arrangement permits wide air gaps to beemployed. With an ordinary linear induction motor, only one row ofelectromagnetics are provided, or two rows of electromagnets areprovided on either side of an air gap with their electromagnet poles andspaces on opposite sides of the air gap being aligned. As the air gap ofexisting linear induction motors is increased, more and more flux isdiverted across the non-magnetic space between adjacent magnetic polesof a given row. For wide air gaps, therefore, wide spaces between polesare required. This is undesirable for the movement of small articlesbecause wide pole spacing results in large areas along the air gap whichhas insufficient flux density. By off-setting the poles on oppositesides of the air gap according to the technique of the presentinvention, the regions along the air gap that contain magnetic flux oftworelative phases are substantially increased for a given number ofelectromagnetic poles. It is the regions of two relative magnetic fluxphases that propel a conductive nonmagnetic article when positionedtherein. If these regions are too far apart, small articles cannot be.propelled, for if an article having a dimension significantly less thanthe distance between successive dual phase flux regions, the article maynot be moved at all.

If a standard linear motor construction is employed in order to obtaindual flux regions close enough together by reducing the non-magneticspace between poles, the air gap must be made smaller than desirable formany applications in order to prevent a significant amount of flux fromtravelling between adjacent poles rather than going across the air gap.In waste separation, a large air gap is desirable so that large wastematerial may pass therethrough for separation of electrically conductivenon-magnetic particles therefrom. A close spacing of dual magnetic fluxphase regions is also desirable for waste material separation so thatsmall articles will be moved by the magnetic forces. A wide air gap isdesirable for moving articles such as aluminum can ends, especially ifthe air gap is in a curved pattern. The magnetic poles arrangement ofthe present invention permits such effective waste separation andarticle moving systems.

The off-set magnetic pole technique of the present invention has afurther advantage that the flux crossing the air gap does so at theedges of the magnetic poles. This flux is thereby of a higher densitylevel than that which occurs in ordinary existing linear inductionmotors. High flux density is important since the forces imparted on anarticle within the air gap vary as a square of the flux density actingupon the article.

Additional feature, objects and advantages of the present invention willbecome apparent from the following description of its preferredembodiments which should be taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows magnetic pole arrangementutilized for the separation of waste material;

the pole arrangements of FIG. 2;

F IG. 2 is a schematic diagram of the magnetic poles of FIG. 1 takenacross section 2-2 thereof;

FIG. 3 and 4 schematically illustrate modifications in FIG. 5 shows avoltage source for the electromagnets of FIG. 1 and 2;

FIG. 6 illustrates schematically-an alternate arrangement of the magnetsof FIG. 1;

FIG. 7 shows a curved article moving path of magnetic poles;

FIG. 8 schematically illustrates a complex magnetic force article movingsystem; and

FIG. 9 illustrates another specific complex force article moving system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a specificembodiment of the magnetic techniques of the present invention isdescribed for separation of electrically conductive nonmagneticcomponents of garbage or other waste material. The lightweightcomponents of the waste material (such as paper) and ferrous metals havealready been removed by other components (not shown) of a complete wastematerial processing and recovery system. The remaining waste material 12is deposited at an end 11 of a conveyor belt 13. The conveyor belt 13 isdriven by rollers 15 and 17 at opposite ends thereof. At least one ofthe rollers is given motion by some appropriate driving mechanism (notshown). As .the conveyor advances, the waste material 12 deposited atthe end 11 passes through an air gap formed between two rows ofelectromagnets. A first row of electromagnets 19, 20, 21, and 22 ispositioned across the width of the conveyor belt 13 at a distance aboveit to permit the waste material to pass thereunder under the influenceof the conveyor belt. A second row of electromagnets 23, 24, 25 and 27are positioned immediately beneath the conveyor belt 13 at a positionacross the conveyor belt 13 directly beneath the first row ofelectromagnets 19-22. Other specific numbers of magnets may be utilizedbut nine electromagents as illustrated in FIGS. 1 and 2 is convenientfor energization by a three phase source.-

The rows of magnets of FIG. I generate eddy currents in non-magneticelectrically conductive material that is positioned in the air gap onthe conveyor belt 13. These eddy currents then generate a magnetic fieldwhich interacts with the magnetic fields existing in the air gap in amanner which tends to move a nonmagnetic electrically conductivearticle, such as an article 29 of FIG. 1, off the side of the conveyorbelt 13 and into some appropriate receptacle 31.

. Other elements of the waste material travelling along the conveyor 13,such as glass, wood, rubber, plastics, rock, etc. are discharged off anend 33 of the conveyor belt 13. The separated non-magnetic metals thatare collected in the receptacle 31 may then be recycled and used again.

Referring to FIG. 2, the magnetic poles of the electromagnets shown inFIG.'l are schematically illustrated in a section to show the relativepositions of the various magnetic poles. These positions are importantin realizing the maximum separation potential of the mechanism ofFIG. 1. Each of the magnetic poles 19-22 of the first row have a width ain a direction along the length of the row while a non-magnetic spacehaving a width b is provided between adjacent magnetic poles of thefirst row. Similarly, the magnetic poles 23-27 of the second row have awidth c and a space between adjacent poles of non-magnetic'material awidth b. An air gap is formed by spacing between the first and secondrows of poles, the width of this air gap being denoted in FIG. 2 by e.The poles of each row are positioned in a direction across the conveyorbelt 13 opposite non-magnetic spaces between poles of the other row ofmagnetic poles.

In the very specific example of the techniques of the present inventionas illustrated in FIG. 2, the pole widths a and c are equal to eachother and to both of the polespacings b and d. The air gap dimension ecan be as large as the magnitude of the pole spacing b or d as requiredfor the specific application. The extremities of each pole face arepositioned substantially directly opposite the extremities of itsopposing non magnetic space.

In order to move electrically conductive nonmagnetic articles under theinfluence of the magnetic fields, the first row of electromagnets 19-22is excited with one relative phase of alternating current while thesecond row of electromagnetics 23-27 are excited with a second relativephase of alternating current. The alternating current relative phasesmay differ by a convenient amount because of standard two-phaseelectrical supply equipment. The result is that'thefirst row ofelectromagnets 19- 22 generate one alternating magnetic .flux path 37.Similarly, the second row of electromagnets23-27 generates a secondalternating magnetic flux in the path 39.'The alternating magnetic fluxin the paths 37 and 39 are out of phase by the phase difference in thealternating current excitation. The result is that in an area 35encompassing both of the magnetic paths 37 and 39, magnetic flux of tworelative phases exist. A non-magnetic, electrically conductive articlewhich finds its way into the dual phase flux region 35 will have anelectrical current generated therein by one of the magnetic'flux phaseswhich then generates a magnetic field that coacts with the other of themagnetic relative flux phases to propelthe article the length of the airgap.

A dimensional variation of the specific'example of FIG. 2 is shown inFIG. 3 wherein each of the pole faces has an equal width but one whichis slightly less than the width of the spaces between the poles. It hasbeen found that a specific pole width of 1.25 inch, a pole spacing of1.5 inch, an air gap of from 1.75 to 2 inches operates satisfactorily inthe embodiment of FIG. 1 to remove non-magnetic metal waste materials.

It is preferable that the pole widths be equal to or somewhat less thewidth of the opposing pole spaces. Although some overlap of pole faces,such as shown in an exaggerated form in FIG. 4, may be satisfactory incertain circumstances, it is not preferred where a wide air gap isrequired or desired. It can be seen from FIG. 4 that a plurality oflarge pole widths results in small non-magnetic spaces between polewidths of this row. This limited pole spacing requires an appropriatelysmall air gap in order to prevent a substantial amount of magnetic fluxfrom travelling across spaces between poles. For this reason, it ispreferred that no overlapping of magnetic pole faces occurs.

It will be noted from FIG. 2 that there are substantially the samenumber of dual phase magnetic flux particles from shredded areas alongthe length of the air gap as there are electromagnetics. There are eightsuch regions generated by nine electromagnetics.

In order to get an equal number of dual phase magnetic flux areas acrossthe conveyor belt 13 by using ordinary linear induction motortechniques, twice as many electromagnets would have tobe utilizedthereacross as shown in FIGS. 1 and 2. However, this would make thepoles and spaces therebetween very small. This would be unsatisfactoryin the examples described herein since the maximum permissible air gapwould then be severely reduced. The maximum size of the air gap islimited by the spaces between electromagnetic poles in each row.

A further advantage of the basic magnetic pole arrangement of thepresent invention is illustrated with respect to FIG. 3. Since fluxpasses between sharp corners at the edges of opposing magnetic poles,the magnetic flux is concentrated over a smaller area. The resultingincreased flux density thus provides additional propelling force tonon-magnetic pieces in the air gap since such a propelling force isproportional to the square of the magnetic flux density. This is anadvan- I tage over a configuration of poles such as that shown in FIG. 4wherein opposing poles overlap each other. In FIG. 4, the magnetic fluxpasses between the parallel faces of the opposing pole portions and isthus not as concentrated as in the configurations of FIGS. 2 and 3.Also, since the magnetic flux between poles of FIG. 3 is concentratedand its density high there is some fringing flux in the air gap betweenpoles that increases the area somewhat through which flux passes. Thisin combination with the large number of dual phase magnetic flux areasalong the width of the conveyor 13 means that very small articles can bemoved by the magnetic fields even with a larger air gap that has beenheretofore possible.

It may be noted that the configuration of FIG. 2, as opposed topositioning the magnetic pole faces opposite one another, results inreducing the speed of a travelling magnetic field across the width ofthe conveyor belt 13. This reduced magnetic field speed results in lessslip and consequently more effective forces for conveying non-magneticmetal along the air gap. Also in the embodiment of FIG. 2, there is anupward/downward travelling field at the entry and exit of the air gap asthe material is being moved therethrough by the conveyor 13. Thesetransitory travelling fields result in a vibratory or shaking motion onnon-magnetic metals being carried by the conveyor 13 and this has thebeneficial result of tending to reduce static friction so that thenon-magnetic metal may be easily removed from the conveyor belt.l3.

The direction of forces on electrically conductive non-magnetic articleswithin the air gap of the rows of electromagnets shown in FIGS. 1 and 2depends upon the relative phases of the two-phase energization thereof.If the phases are reversed between the first and second rows ofelectromagnets, the direction of travel across the width of the conveyorbelt 13 will be reversed. Other useful moving and guiding functions maybe performed by the electromagnet by even different phasing. If theelectromagnets l9 and 20 are energized with one phase of a two-phasealternating current supply which results in moving a non-magnetic metalto the right in FIG. 2, the energization of electromagnets 21 and 22with the other alternating current supply phase tends to move sucharticles in their regions of influence to the left. The result is thetendency to center electrically conductive non-magnetic articles on theconveyor belt 13 as the articles pass through the air gap. By reversingthe relative phases of the electromagnets l9-22 once again, sucharticles can be forced off I of both edges of the conveyor belt 13. Manysuch possibilities of movement of such articles are possible by variousphase relationships of alternating current exci- Electromagnet: 23 I9 2420 25 21 26 22 27 Phase A X X X Phase B X X X Phase C X X X If it isdesired to produce forces from the right to the left in FIG. 2, thevarious electromagnets are phased as follows:

Electromagnet: 23 19 24 20 25 21 26 22 27 Phase A 1 X X X Phase B X X XPhase C X X X If it is desiredto produce forces from either end of therows of electromagnets toward the center, the following relative phasingis applied:

Electromagnet:

23 I9 24 20 25 2] 26 22 27 Phase A X X X X Phase B X X X Phase C X X Ifit is desired to have forces on articles directed from the center of therows of electromagnets to both ends, the following relative phasing ofthe electromagnets is applied:

Electromagnet: 23 I9 24 20 25 21 26 22 27 Phase A X X Phase B X X XPhase C X X X X In the embodiment of FIGS. 1 and 2, very small pieces ofnon-magnetic metal to be removed from the conveyor belt 13 couldpossibly avoid strong dual phase magnetic flux areas in the air gap andthus not be diverted off of the conveyor. In order to remove more of thevery small pieces, in the order of one-half the width of the pole face,the poles may be angled as shown in FIG. 6, which is a top view of aconveyor belt installation. Since the operable areas of dual phase fluxoccur at the corners of opposing poles, it is seen that a non-magneticmetal piece 41 travelling on the conveyor belt 13 crosses throughseveral such dual phase magnetic flux areas and is thrown off theconveyor belt by travelling in a path 43.

It should be understood that a number of magnetic removal stages may beemployed along theconveyor belt 13, some angled as in FIG. 6 and somestraight as in FIG. 1. The various stages could have different air gapsizes depending upon the expected sizes of material at the variousstagesalong the conveyor belt. Furthermore, not all of the stages needto have an electromagnetic pattern to throw the articles off theconveyor belt but rather one stage could merely guide all nonmagneticelectrically conductive articles into the center of the conveyor beltfor separation by a later stage. The possibilities for variouscombinations of stages of magnetic poles according to the presentinvention are numerous depending upon the specific article movement jobthat is required to be done. Additionally, the waste material can beallowed to drop "by gravity through a properly positioned magnetic airgap rather than using a conveyor belt for propulsion.

Besides applications to waste removal systems, the magnetic poleconfiguration described with respect to the Figures may also be appliedfor moving electrically conductive non-magnetic articles, such asaluminum can lids, from one point to another. Thp more efficientlygenerated electromagnetic forces are utilized as a primary moving sourcerather than as a mere diversion from some other primary moving forcesuch as a conveyor belt. Referring to FIG. 7, one application ofmovingaluminum can lids is illustrated wherein one very long row ofpoles 45 opposes spaces between mag netic poles of a second row 47. Sucha configuration can be used, with the addition of some can lidsupporting surface, for moving an aluminum can lid 49 from one point toanother between ends of the rows of magnets. The magnets can be laid outto form a flat horizontal path in which the aluminum can lid 49 ispropelled in a horizontal position, or the magnets may be placed so thatthe air gap' is vertical and the aluminum can lid is somewhat rolledalong in the air gap. The relative energization of the magnets along thealuminum can lid path is preferably with three-phase electric current ina manner described with respect to FIG. 2.

Since large air gaps are possible with the system of the presentinvention, the opposing rows of magnets for an aluminum can lidpropelling system may be curved as specifically shown in FIG. 7. Such acurved section is especially useful in a can plant for moving aluminumcan lids since a continuous path is possible, including a path from awork station up and over an aisle and backdown to another work station.The curved sections such as shown in FIG. 7 make such continuousmovement possible. Presently, discrete straight line conveying systemsare used wherein the output of one conveying section becomes the inputto another, etc., in a very complicated and noisy system.

In conjunction with the magnetic propulsion system for articles such ascan ends, the techniques of the present invention may be applied to forman additional guiding, centering, or. diverting capability. Referring toFIG. 8, thesolid circles, such as a circle 51, represent a magnetic poleabove the articles to be conveyed. The dotted circles, such as a circle53 of FIG. 8, represent a magnetic pole beneath the articles to beconveyed. The letters on the center of the schematic circle repre- Acenter row 55 of electromagnets positioned according to the techniquesof the present invention is provided for propelling an article such anan aluminum can end 57 from the left to the right along therow 55. Inconjunction with this, however, are rows 57 and 59 of electromagnetswhich are phased to also provide a propelling force from left to right.Additionally, the relative phases of the electromagnets of the rows 57and 59 are chosen with respect to the relative phases of the row 55 toprovide diverting electromagnetic forces therebetween, as shown by thearrows. That is, the rows 55 and 57, for instance, are both phased toprovide propelling forces from left to right and the relative phasesbetween the adjacent magnets of the rows 57 and 55 are such to providelateral forces that tend to propel an article out of row 55 and into therow 57. Both of the rows 57 and 59 would not be energized to divert canlids alternately from row 56 to row 57 and then to row 59.

Additional rows of electromagnets 61 and 63 are provided in, order tocomplete the diversion of articles from the center row 55. Of course,further rows of electromagnets could be provided depending upon themagnitude of the lateral diversion of articles such as can lids that isdesired. It will be recognized that by changing phases of adjacentmagnets that forces can be altered'and thus a desired path of movementof an article can be controlled. One such modification is to reverse theleft to right forces of the magnets by changing the phasing so that thepropelling forces on articles is from the right to the left of theexample of FIG. 8. Relative phasing would also be changed so that thelateral forces between rows tended to move can lids from the extremerows 61 and 63 to the center row 55. Can lids from two separate sourcerows are then propelled to the left of FIG. 8 and into a common streamin the center row 55.

Referring to FIG. 9, another variation of lateral diverting magneticforces is illustrated. A center row 65 of electromagnets arrangedaccording to the offset pole concepts of the present'invention areconnected to a three-phase alternating current source in a manner toprovide propelling forces from the left to the right of FIG. 9. Rows ofmagnets 67 and 69 on alternate sides of the middle row 65 are alsoconnected to have relaternating current excitation from a three-phasesource,

such as that illustrated in FIG. 5.

tive phases in order to provide propelling forces from left to right.Additionally, the rows 67 and 69 are phased with respect to the centerrow 65, as shown by the arrows of FIG. 9. The result of theconfiguration shown in FIG. 9 is to provide electromagnetic centering ofarticles as they are propelled from left to right. This eliminates thenecessity for mechanical orother forms of centering guides and thuseliminates a great source of noise in such conveying systems.

Although the various aspects of the present invention have beendescribed with respect to specific examples thereof, it will beunderstood that the invention is entitled to protection within the fullscope of the appended claims.

I claim:

1. A magnetic pole arrangement for giving motion to electricallyconductive materials, comprising:

a first row of a plurality of electrically excitable magnetic pole facesforming one side of an air gap, said first row pole faces beingpositioned with spaces therebetween along said first row,

a second row of a plurality of electrically excitable magnetic polefaces forming an opposite side of said air gap, said second row polefaces being positioned with spaces therebetween along said second row,

each pole face of the first row being positioned opposite a space ofsaid second row and having a width substantially equal to that of saidopposite space, and

each pole face of the second row being positioned opposite a space ofsaid first row and having a width substantially equal to that of saidopposite space.

2. The magnetic pole arrangement of claim 1 which additionally comprisesmeans for electrically exciting the magnetic pole faces with alternatingcurrent to provide magnetic flux of two distinct relative phases betweeneach pole face and those pole faces adjacent a space opposite said poleface.

3. The magnetic pole arrangement of claim 1 which additionally comprisesmeans connecting the electrically excitable magnetic pole faces to apoly-phase alternating electrical power source for producing a magneticfield therefrom having one of a plurality of relative alternatingphases, each pole face of the second row generating a magnetic fieldhaving a relative phase different from that of two poles of the firstrow on either side of a pole space located opposite said each pole.

4. The magnetic pole arrangement of claim 1 wherein all of said spacesbetween pole faces are substantially equal in width along theirrespective rows and wherein said gap width between said first and secondrow of pole faces is substantially equal to the width of said spaces.

5. Apparatus for removing electrically conductive particles from astream of waste material, comprising:

means for forming waste material including electrically conductive andelectrically non-conductive particles into a stream along a given path,

a plurality of electromagnetic poles arranged in a first row extendingacrosssaid stream given path with non-magnetic material spaces betweensaid poles,

a plurality of electromagnetic poles positioned in a second rowextending across said stream given path on its side opposite to thelocation of the first row and having non-magnetic material spacesbetween said poles, the poles of each row being oriented directlyopposite a space of the other row, and

means for energizing said electromagnets of the first and second rowswith alternating current of various relative phases in a manner to exertforce upon electrically conductive particles positioned in said streamthat is in a direction along said rows, whereby conductive particles areremoved out of a stream of waste material. 7 Y 7 H 6. Apparatusaccording to claim 5 wherein each pole has a dimension along its rowthat is substantially equal to a space of the other row opposing saideach pole.

7. Apparatus according to claim 5 wherein said stream forming meansincludes a substantially horizontal conveyor belt .with said first rowof electromagnetic poles extending across the belt on its underside andsaid second row of electromagnetic poles extending across the belt adistance above its top side.

8. Apparatus according to claim 7 wherein said first and second rows areoriented at a finite angle less than 90 with the conveyor belt.

9. Apparatus for giving motion to electrically conductive non-magneticarticles such as aluminum can lids, comprising:

a first row of a plurality electromagnetic poles extending along a pathover which said articles are to conveyed, said poles being separatedalong 10 the path by spaces of non-magnetic material,

a second row of a plurality electromagnetic poles extending along saidpath and separated from said first row by an air gap through which saidarticles are given motion, the poles of the second 5 row being separatedalong the path from each other by spaces of non-magnetic meterial,

each of the poles of said first and second rows being l positionedopposite a space of the opposing row of poles, and

means for energizing the electromagnetic poles with rial and orientedwith poles and spaces aligned with those of the first row,

a fourth row of electromagnetic poles positioned alongside said secondrow, said fourth row of poles being separated by spaces of non-magneticmaterial and oriented with poles and spaces aligned with those of thesecond row, thereby to form a second path along which said articles maybe conveyed in an air gap between said third and fourth rows, andwherein said energizing means includes means for en- 40 ergizing theelectromagnetic poles of the first, second, third and fourth rows tosimultaneously exert forces on an article along the lengths of saidpaths and between said paths, whereby an article may be given complexmotion.

12. Apparatus according to claim 5 wherein said energizing meansprovides magnetic flux of two distinct relative phases between each poleface and those pole faces adjacent a space opposite said pole face.

13. Apparatus for giving motion to an electrically conductivenon-magnetic article, comprising:

a' first row of a plurality electromagnetic poles extending along adefined path over which said article is to be moved, said poles beingseparated along the path by spaces of non-magnetic.

a second row of a plurality electromagnetic poles extending along saidpath and separated from said first row by an air gap through which saidarticle is to be moved, the poles of the second row being separatedalong the path from each other by spaces of non-magnetic material.

each of the poles of said first and second rows being positionedopposite a space of the opposing row of poles, and

means for energizing the electromagnetic poles with alternating currentto provide magnetic flux of two distinct relative phases between eachpole face and those pole faces adjacent a space opposite said each poleface.

I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION pa 3,824,516Dated July 16, 1974 lnventofls) Sander Benowitz It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 49, "Three" should read These' Co1umn 7, litre- 23, "Thp"should read The Column 10, line 9, after "to" insert be line 55, after"non-magnetic" insert material Signed and sealed this 29th day ofOctober 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Conmnissioner ofPatents USCOMM-DC 60376-P69 u s covzwmzu'r PRINTING OFFXCEa 8 93 0 FORMPO-1050 (IO-69) I UNITED STATES PATENT OFFICE. CERTIFICATE OF CORRECTIONPatent No. 3,824,516 Dated ly I6, 1974 lnventol-(s) Sander Benowitz Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 49, "Three" should read These' Co1umn 7, lir le 23, "Thp"should read The Column 10, line 9, after "to" insert be line 55, after"non-magnetic" insert material Signedjand sealed this 29th day ofOctober 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents USCOMM-DC 60376-P69 u s covznnuzm PRINYING OFFICE: a 93 0 FORMPO-1050 (10-69)

1. A magnetic pole arrangement for giving motion to electricallyconductive materials, comprising: a first row of a plurality ofelectrically excitable magnetic pole faces forming one side of an airgap, said first row pole faces being positioned with spaces therebetweenalong said first row, a second row of a plurality of electricallyexcitable magnetic pole faces forming an opposite side of said air gap,said second row pole faces being positioned with spaces therebetweenalong said second row, each pole face of the first row being positionedopposite a space of said second row and having a width substantiallyequal to that of said opposite space, and each pole face of the secondrow being positioned opposite a space of said first row and having awidth substantially equal to that of said opposite space.
 2. Themagnetic pole arrangement of claim 1 which additionally comprises meansfor electrically exciting the magnetic pole faces with alternatingcurrent to provide magnetic flux of two distinct relative phases betweeneach pole face and those pole faces adjacent a space opposite said poleface.
 3. The magnetic pole arrangement of claim 1 which additionallycomprises means connecting the electrically excitable magnetic polefaces to a poly-phase alternating electrical power source for producinga magnetic field therefrom having one of a plurality of relativealternating phases, each pole face of the second row generating amagnetic field having a relative phase different from that of two polesof the first row on either side of a pole space located opposite saideach pole.
 4. The magnetic pole arrangement of claim 1 wherein all ofsaid spaces between pole faces are substantially equal in width alongtheir respective rows and wherein said gap width between said first andsecond row of pole faces is substantially equal to the width of saidspaces.
 5. Apparatus for removing electrically conductive particles froma stream of waste material, comprising: means for forming waste materialincluding electrically conductive and electrically non-conductiveparticles into a stream along a given path, a plurality ofelectromagnetic poles arranged in a first row extending across saidstream given path with non-magnetic material spaces between said poles,a plurality of electromagnetic poles positioned in a second rowextending across said stream given path on its side opposite to thelocation of the first row and having non-magnetic material spacesbetween said poles, the poles of each row being oriented directlyopposite a space of the other row, and means for energizing saidelectromagnets of the first and second rows with alternating current ofvarious relative phases in a manner to exert force upon electricallyconductive particles positioned in said stream that is in a directionalong said rows, whereby conductive particles are removed out of astream of waste material.
 6. Apparatus according to claim 5 wherein eachpole has a dimension along its row that is substantially equal to aspace of the other row opposing said each pole.
 7. Apparatus accordingto claim 5 wherein said stream forming means includes a substantiallyhorizontal conveyor belt with said first row of electromagnetic polesextending across the belt on its underside and said second row ofelectromagnetic poles extending across the belt a distance above its topside.
 8. Apparatus according to claim 7 wherein said first and secondrows are oriented at a finite angle less than 90* with the conveyorbelt.
 9. Apparatus for giving motion to electrically conductivenon-magnetic articles such as aluminum can lids, comprising: a first rowof electromagnetic poles extending along a path over which said articlesare to be conveyed, said poles being separated along the path by spacesof non-magnetic material, a second row of electromagnetic polesextending along said path and separated from said first row by an airgap through which saiD articles are given motion, the poles of thesecond row being separated along the path from each other by spaces ofnon-magnetic material, each of the poles of said first and second rowsbeing positioned opposite a space of the opposing row of poles, andmeans for energizing the electromagnetic poles with alternating currentof various relative phases in a manner to exert force on an article inthe air gap in a direction along said path.
 10. Apparatus according toclaim 9 wherein said path includes a curved section.
 11. Apparatusaccording to claim 9 which additionally comprises: a third row ofelectromagnetic poles positioned alongside said first row, said thirdrow of poles being separated by spaces of non-magnetic material andoriented with poles and spaces aligned with those of the first row, afourth row of electromagnetic poles positioned alongside said secondrow, said fourth row of poles being separated by spaces of non-magneticmaterial and oriented with poles and spaces aligned with those of thesecond row, thereby to form a second path along which said articles maybe conveyed in an air gap between said third and fourth rows, andwherein said energizing means includes means for energizing theelectromagnetic poles of the first, second, third and fourth rows tosimultaneously exert forces on an article along the lengths of saidpaths and between said paths, whereby an article may be given complexmotion.
 12. Apparatus according to claim 5 wherein said energizing meansprovides magnetic flux of two distinct relative phases between each poleface and those pole faces adjacent a space opposite said pole face. 13.Apparatus for giving motion to an electrically conductive non-magneticarticle, comprising: a first row of electromagnetic poles extendingalong a defined path over which said article is to be moved, said polesbeing separated along the path by spaces of non-magnetic a second row ofelectromagnetic poles extending along said path and separated from saidfirst row by an air gap through which said article is to be moved, thepoles of the second row being separated along the path from each otherby spaces of non-magnetic material, each of the poles of said first andsecond rows being positioned opposite a space of the opposing row ofpoles, and means for energizing the electromagnetic poles withalternating current to provide magnetic flux of two distinct relativephases between each pole face and those pole faces adjacent a spaceopposite said each pole face.